PLAINSBORO -- More than 150 law enforcement officers joined about 30 leaders from the New Jersey chapter of the NAACP for a conference on "fair and impartial policing" Thursday.

The voluntary training, which officials described as "historic," was part of the state NAACP's annual convention, held this year at the Westin in Plainsboro. It was run by Noble Wray, a policing expert and former chief of the Madison, Wisc. police department.

Advocates for the method say that biased policing is not a symptom of widespread racism or prejudice within departments, but the product of unconscious biases that everyone holds. The training focuses on "the psychology of bias," and was sponsored by the NAACP, the state Attorney General's Office, and the New Jersey Chiefs of Police Association.

At a press conference following the day-long session, officials said participants, from suburban police chiefs to urban community activists, engaged in frank discussions about their own implicit biases. (The discussions were so frank that the session was closed to the press, so participants could speak freely, they said.)

"It's not just the police and certain community groups, it's all of humanity," said Denville Police Chief Christopher Wagner, the current president of the state Chiefs of Police Association. "We all have (biases), and we're not going to fix them today. I'm just more aware of the biases that I have, and by being aware of them -- keenly aware of them -- I can react differently to situations."

Asked if national scrutiny of interactions between police and minority groups -- spurred by high-profile police shootings in Ferguson, Mo., Baltimore, and elsewhere -- had swelled attendance numbers for the training, acting Attorney General John Hoffman agreed.

"There is a realization that to be an effective law enforcement organization, there must be positive, respectful, dignified and constructive interaction with the community," he said.

But Hoffman repeatedly told reporters that New Jersey law enforcement agencies have been especially "progressive" when it comes to community policing, "not just in establishing a relationship (with communities), but a partnership."

The state has a storied history of racial profiling, however: The State Police were under federal oversight for a decade until 2009, in part due to rampant racial profiling along the New Jersey Turnpike, and the Newark Police Department was subjected to similar monitoring just last year.

New Jersey has also seen its share of public outcry over police shootings, and earlier this week, the U.S. Attorney's Office acknowledged it had met with the families of three such men, amid calls for federal civil rights investigations.

Richard Smith, head of the state NAACP, said Thursday that African-Americans and other minority communities bring their own biases to bear in interactions with police, and the groups need to find common ground to improve policing in urban communities.

"Our community is also embracing the thinking of collective responsibility, escaping the sick 'no snitch' mentality that destroys our communities and make police ineffective in their attempt to make our communities safe," Smith said, later adding: "We need police, and the police need us."

S.P. Sullivan may be reached at ssullivan@njadvancemedia.com. Follow him on Twitter. Find NJ.com on Facebook.